Acid Phosphatases from Different Tissues Purification, Isoenzymes, and Properties

Acid Phosphatases from Different Tissues Purification, Isoenzymes, and Properties 

Study of the distribution of acid phosphatase in different tissues is burdened by indications that there are several acid phosphatases. Even the older literature indicated the nonidentity of acid phosphatases of different origin. In 1934, Davies (D4) showed that the acid phosphatase in the red cell hydrolyzed a-glycerophosphate more readily than )8-glycerophosphate, whereas the reverse was true for the acid phosphatase from spleen. Kutscher and Wolbergs (K12) found that prostatic acid phosphatase was inactivated irreversibly by various narcotics, including alcohols. 

A more systematic study of the acid phosphatases of erythrocytes and of human prostate was undertaken in 1949 by Abul-Fadl and King (A4). The preparations were crude, the prostatic phosphatase being obtained by grinding human prostate with a 5-fold volume of 0.9% NaCl. The erythrocytic phosphatase consisted of centrifuged red cells, separated from white cells, washed twice with 0.9% NaCl and hemolyzed in 9 volumes of water. The buffer-substrate mixture consisted of equal volumes of acetate buffer (concentration not stated) and 0.02 M disodium phenyl phosphate. 

The erythrocytic acid phosphatase from man and several other species showed two pH optima, one at a range of pH 4.3-4.8 and the second at pH 5.0-5.7. A concentration of 0.01 M Mg inhibited these activities to the extent of about 30-50% at the lower pH levels and somewhat less so in the region of the higher pH optimum. Human prostatic acid phosphatase showed one clear pH optimum, at about 5.0-5.2, and the inhibition by 0.01 M Mg + was about 30% in this region. 

The relative rates of hydrolysis of several substrates were determined at 37°C and pH 5.0 and expressed as milligrams of phosphorus liberated in 30 minutes per 100 ml of a diluted enzyme preparation. For 0.02 Af yS-glycerophosphate in the absence of any added Mg these rates were 0.2 for erythrocytic phosphatase and 29 for prostatic phosphatase. The corresponding rates were 11 and 28 with 0.02 M a-glycerophosphate as substrate, and 55 and 53 with 0.005 M phenyl phosphate as substrate. The presence of Mg activated the rates of hydrolysis to only a small degree. Thus, it may be seen that the use of /8-glycerophosphate as substrate distinguished sharply between the erythrocytic and prostatic phosphatases. 

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